B344-21-880 Issue N
Page 16 © Edwards Limited 2007. All rights reserved.
Edwards and the Edwards logo are trademarks of Edwards Limited.
Installation
3.3 Locate the pump
The Diffstak pump is designed to operate with the inlet-flange horizontal and at the top. Locate the pump within
practical working distance from suitable electrical supplies, cooling-water and compressed-air supplies (where
applicable).
3.4 Vacuum connections
Typical configurations of a vacuum system in which a Diffstak pump is installed are shown in Figures 18 and 19. The
Edwards components required to connect the backing and roughing pipelines are shown in Figures 12 and 13. Some
of these components are supplied in the fitting-kit; the supplied components are identified in the keys to these
figures. The Item Numbers of other components are given in Section 7.
3.4.1 Diffstak inlet
The ISO compatible inlet-flanges on the valved Diffstak 63/150, 100/300 and 160/700 pumps can be bolted to any
flat, unscratched surface; use the Co-Seal supplied with the Diffstak to obtain a reliable vacuum seal (see Figure 9).
Seal the inlet-flange of Diffstak 250/2000 pumps with the trapped ‘O’ ring supplied with the pump.
Use a rotatable-flange and Co-Seal or a Co-Seal and clamps with unvalved C-model Diffstaks (see Figure 11).
The Diffstak 100/300F and 160/700F pumps have ConFlat flanges for copper compression gaskets (see Figure 10).
Before you connect the pump-inlet, clean the flange with acetone or another suitable cleaning solution.
The inlet-flange on M-, P- and F-model pumps has a number of equally spaced fixing-holes for connection of the pump
to your system. Figure 8 shows the arrangement of fixing-holes on the inlet-flange PCD (pitch circle diameter) and
details of the use of bolts or studs to fit the inlet-flange.
Use the correct number and size of bolts or studs to connect the pump inlet-flange. Table 1 shows the required bolt/
stud lengths, the number of flange holes in the inlet-flange and the fixing-hole PCD for the different Diffstak pump
models. Fit the bolts or studs and the nuts, then tighten them alternately and evenly to a torque of 5 Nm, so that
the seal is evenly loaded. If the seal is not evenly loaded, the seal may leak.
If the pump is not directly flange mounted to the vacuum system, you must provide additional
support to ensure that the pump is stable and supported. If you do not and the pumps falls or
topples, there is a risk of damage to the equipment or injury to people.
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